Background
Handheld ultrasound is emerging as an important tool for point-of-care cardiac assessment. Although cardiac ultrasound skills are traditionally introduced during postgraduate training, the optimal time and methodology to initiate training in focused cardiac ultrasound (FCU) are unknown. The objective of this study was to develop and evaluate a novel curriculum for training medical students in the use of FCU.
Methods
The study was conducted in two phases. In the first phase, 12 first-year medical students underwent FCU training over an 8-week period. In the second phase, 45 third-year medical students were randomized to one of three educational programs. Program 1 consisted of a lecture-based approach with scan training by a sonographer. Program 2 coupled electronic education modules with sonographer scan training. Program 3 was fully self-directed, combining electronic modules with scan training on a high-fidelity ultrasound simulator. Image interpretation skills and scanning technique were evaluated after each program.
Results
First-year medical students were able to modestly improve interpretation ability and acquire limited scanning skills. Third-year medical students exhibited similar improvement in mean examination score for image interpretation whether a lecture-based program or electronic modules was used. Students in the self-directed group using an ultrasound simulator had significantly lower mean quality scores than students taught by sonographers.
Conclusions
Third-year medical students were able to acquire FCU image acquisition and interpretation skills after a novel training program. Self-directed electronic modules are effective for teaching introductory FCU interpretation skills, while expert-guided training is important for developing scanning technique.
Recent developments in ultrasound technology have enabled point-of-care cardiac assessment of patients using portable, handheld ultrasound (HHU) units. The American Society of Echocardiography (ASE) has recognized that these devices are capable of performing focused cardiac ultrasound (FCU) assessments as an adjunct to the physical examination. The ASE has also noted that comprehensive echocardiographic examination requires image acquisition by trained sonographers and image interpretation by skilled echocardiographers. Although the opportunity for widespread use of HHU exists, the appropriate clinical applications of FCU are yet to be clearly defined.
The potential clinical utility of FCU has been well established. However, no studies have attempted to elucidate the optimal timing and methodology to educate trainees in the use of FCU. Current research has focused on the application of FCU in clinical settings; published training programs have not been well validated. Several international bodies have recognized the need to train nonexpert imagers; however, a consensus does not exist regarding the most appropriate timing and method of training. Considering that this technology is available for use in a broad range of settings, a lack of standardized training is concerning.
The majority of studies examining FCU have focused exclusively on the proficiency of attending staff members and postgraduate trainees. There has been comparatively little research focusing on introduction of FCU training during undergraduate medical education. Because medical school is the stage at which fundamental clinical examination skills are introduced, training in FCU may be most effective during this period. Considering the increasing prevalence of ultrasound use, competence in sonographic examination may become a core competency required of graduating medical students.
The objective of this study was to develop and evaluate three novel curricula for training medical students in the acquisition and interpretation of FCU. The educational programs were designed to provide students with a basic skill set for the assessment of cardiac patients using an eight-view FCU protocol. The study was conducted in two phases to (1) assess the time at which the introduction of FCU skills would be appropriate and (2) assess the optimal methodology (didactic teaching, electronic modules, or simulation training) to deliver this fundamental knowledge.
Methods
The study was conducted in two phases. The first phase was designed to establish the feasibility of first-year medical students to acquire FCU interpretation and image acquisition skills. The second phase was conducted in a larger cohort of third-year medical students and investigated different methods of delivering knowledge and skills, including electronic and simulation-based modules. The Queen’s University Research Ethics Board approved the study protocols, and written consent was obtained from all participants.
Phase 1
Study Population
Twelve medical students from the Queen’s University School of Medicine were recruited to participate in this project during the summer break after their first year of medical education. Students had not completed their core training in cardiology. Exclusion criteria included any preexisting ultrasound or echocardiography experience. No students met these criteria, thus none were excluded. This study was extracurricular, and no compensation, monetary or academic credit, was provided for participation.
HHU Device
The Vscan device (GE Healthcare, Horton, Norway) used in this study consists of a display unit and a broad-bandwidth, phased-array probe (total weight, 390 g). It provides two-dimensional imaging and conventional color flow echocardiographic images. It has limited controls for adjusting image depth and gain. Electronic calipers and a touchpad enable the user to make distance and area measurements. All images can be frozen and scrolled for review, but there is no electrocardiographic gating. Images may be saved in still or video format.
Cardiac Pathologies
Five cardiac pathologies were examined: left ventricular (LV) systolic dysfunction, LV hypertrophy, aortic valve dysfunction (regurgitation and stenosis), mitral valve dysfunction (regurgitation and stenosis), and pericardial effusion ( Table 1 ). The cardiac pathologies were selected on the basis of consensus by three ASE level III echocardiographers at our institution. All FCU images provided to students for assessment depicted abnormalities rated as moderate or severe by ASE level III echocardiographers; this level of pathology was considered representative of clinically relevant abnormalities. Students were not expected to grade pathologies on the basis of severity; assessment of images was based exclusively on identification of the presence of a moderate or severe abnormality.
| Pathology | Interpretation Method |
|---|---|
| Aortic valve dysfunction (moderate to severe regurgitation or stenosis) | Abnormal leaflet thickening, mobility Conventional color flow with visual assessment |
| Mitral valve dysfunction (moderate to severe regurgitation or stenosis) | Conventional color flow with visual assessment |
| LV hypertrophy (moderate to severe) | Qualitative analysis on the basis of visual estimate of wall thickness |
| LV systolic dysfunction (moderate to severe) | Visual estimate of LV systolic contractility |
| Pericardial effusion (moderate to severe) | Visual estimate of pericardial space for presence/absence of effusion |
Preintervention Evaluation
Participants underwent an evaluation of FCU interpretation knowledge before commencing the educational intervention. This evaluation consisted of 15 online case-based multiple-choice questions. Each question consisted of a one-line clinical vignette and a video showing an FCU assessment. Participants were then asked to identify the presence of major cardiac pathology if any was present. Three examples of each of the five cardiac pathologies were presented.
Educational Intervention
The educational intervention was created in consultation with National Board of Echocardiography, ASE level III, and FASE certified echocardiographers and American Registry for Diagnostic Medical Sonography certified sonographers. The program was designed to instruct the participants in image acquisition and interpretation of focused cardiac imaging using HHU units.
The educational intervention included instruction in image acquisition using a focused protocol consisting of seven specific views: apical two-chamber (A2C), apical four-chamber, apical five-chamber (A5C), parasternal long-axis (PLX), and parasternal short-axis (PSX) with cuts at the aortic valve, mitral valve, and midchamber left ventricle (PSX-LV). The intervention occurred over an 8-week period with a 2-hour session each week. Each 2-hour session was divided into a didactic and a practical component. The eight didactic lectures focused on instruction surrounding general cardiac anatomy, general cardiac ultrasound, device use, and the five pathologies described in Table 1 . All lectures were delivered by ASE level III echocardiographers.
Six 1-hour practical instructional sessions focused on FCU scanning technique. Practical sessions were taught by both ASE level III echocardiographers and American Registry for Diagnostic Medical Sonography certified sonographers. Participants were instructed in the use of the HHU unit and proper sonography technique to improve their image accuracy and quality. Participants worked in pairs or small groups with the HHU units to develop their sonographic technique under the direct supervision of the instructors. The remaining two 1-hour practical sessions focused on teaching cases developed from FCU examinations of hospital inpatients. The final element of the educational intervention involved self-directed learning; participants were provided unlimited access to the HHU units and dedicated examination rooms for self-directed practice sessions. The self-directed portion was not a required element of the intervention and thus was not formally quantified.
Postintervention Evaluation
Evaluation of the education intervention was composed of two elements: (1) interpretation knowledge and ability and (2) image acquisition accuracy and quality. Interpretation knowledge and ability was evaluated using an online 15-question, case-based, multiple-choice examination that was identical in structure to the preintervention examination described above. Image acquisition was assessed via an objective structured clinical examination, during which participants were required to obtain seven defined views within a 15-min time period on a healthy volunteer patient. These views were captured, downloaded, and compiled for scoring. Each view was evaluated by an ASE level III echocardiographer blinded to the HHU unit operator. Each view was assigned a composite score on the basis of subjective image quality (1 = excellent, 2 = good, 3 = fair, 4 = poor).
Data Analysis
Multiple-choice examination scores were compiled and tabulated. Data were exported into SPSS version 17.0 for Windows (SPSS, Inc, Chicago, IL) for analysis. Mean scores were calculated for each individual, pathology, and the cohort for both the preintervention and postintervention evaluations. Mean improvement was calculated for each of these categories. Paired t tests were used to compare improvement from preintervention to postintervention for individuals and the cohort. P values < .05 were deemed significant. Improvement in scores by pathology was compared from before to after the intervention. Exact P values were obtained using Bowker’s test of symmetry. Mean scanning scores were tabulated for each participant, view, and the cohort and compared using repeated-measures analysis of variance.
Phase 2
Study Population
Forty-five third-year medical students from the Queen’s University School of Medicine were recruited to participate in this study. All students were in their third year of medical school and had completed their core teaching unit in cardiology before the study. Exclusion criteria were identical to those of phase 1; none of the phase 2 students had participated in phase 1. Students were randomized into one of three educational programs using a random-number generator and were assigned unique identification numbers for the duration of the study.
Cardiac Pathologies
The same cardiac pathologies and interpretation methodology used in phase 1 were used in phase 2 ( Table 1 ).
Preintervention Assessment
After randomization, baseline knowledge of FCU was assessed using an online multiple-choice examination comprising 20 questions, each based on a different FCU cine movie. Ten cases involved normal cases and required students to identify the FCU view shown or identify an aspect of cardiac anatomy. The remaining 10 cases involved two examples of each of the five pathologies; for aortic and mitral valve dysfunction, one example of regurgitation and one example of stenosis was used for each valve ( Table 1 ). Students were required to report their confidence in each answer (on a scale ranging from 0% to 100% in 10% intervals).
Educational Interventions
A novel 4-week FCU curriculum was developed through collaboration with ASE level III echocardiographers and experienced medical educators. This curriculum was delivered via three distinct educational programs ( Table 2 ). Each education program consisted of two components: a “fundamental education unit” that focused on teaching the fundamental principles of cardiac ultrasound and image interpretation and a “scanning education unit” that focused on instruction of FCU scanning technique and image acquisition. Scanning education focused on eight views: the seven views used in phase 1 and a PSX cut of the LV apex. All training sessions were voluntary and conducted entirely outside of the standard medical school curriculum. Sessions were conducted in the School of Medicine building at Queen’s University. To evaluate compliance with the educational protocol, attendance was taken at each training session; however, compliance with self-directed learning components of the curriculum was not formally assessed.
| Educational program 1 | Educational program 2 | Educational program 3 | |
|---|---|---|---|
| Fundamental education | Didactic sessions | Electronic modules | Electronic modules |
| Scanning education | Sonographer training | Sonographer training | Simulation training |
Didactic Education
The didactic component of the educational programs was delivered in four 2-hour lectures over the course of 2 weeks. These sessions were conducted by two expert (ASE level III) staff echocardiographers with extensive experience in medical education. Each session was designed to address specific topics and meet predefined objectives that aligned with the overall educational program goals ( Table 3 ). Didactic content was delivered using interactive PowerPoint presentations (Microsoft Corporation, Redmond, WA) and case-based discussion in a small-group format (15 students).
| Session | Topic/content | Objective |
|---|---|---|
| 1 (2 h) | Introduction to fundamental principles of FCU Review of cardiac anatomy |
|
| 2 (2 h) | Basic echocardiographic views Introduction to scanning technique |
|
| 3 (2 h) | Valvular abnormalities (aortic and mitral) |
|
| 4 (2 h) | LV systolic dysfunction and hypertrophy Pericardial effusion |
|
Electronic Learning Modules
Three interactive online electronic learning modules were designed specifically for this study to deliver identical content as the didactic lectures. These modules were created using the MEdTech platform, an electronic interface purpose-built for the Queen’s University School of Medicine. The modules were designed by study investigators in conjunction with medical educators and an expert MEdTech programmer and Web developer. Modules were accessible to students in educational programs 2 and 3 for a defined 2-week period during the study. Students were able to access the modules at any time during the study period (either on campus or from remote locations using their institutional accounts).
The first module introduced the basic fundamentals of FCU, including physics, clinical applications, and FCU scanning theory. It was designed to provide foundational knowledge regarding FCU to the participants, who had no previous ultrasound or echocardiography experience. This module was intended to be completed over approximately 2 hours.
The second module focused on developing image acquisition skills with the HHU device. The basic functions of the device were outlined using diagrams, video, and text. The standard echocardiographic views to be included in the focused cardiac assessment were described with text and example videos obtained using the HHU device. A major component of this module was a series of nine tutorial videos that led the students through a complete FCU assessment on a patient using the HHU device. This included instructional videos on patient positioning, positioning of the probe for each view, cardiac anatomy using FCU, and troubleshooting. This module was intended to be completed over approximately 4 hours.
The third module provided education on the interpretation of the predetermined pathologies. A systematic approach to image interpretation was described. In addition, a brief review of the various imaging views was provided. The predefined pathologies were described in terms of anatomy, etiologies, and pathophysiology. Annotated figures and videos of specific pathology were provided as the main instructional tool. Finally, video examples with annotations were provided for self-assessment. This module was intended to be completed over approximately 4 hours.
Sonographer-Directed Scanning Tutorials
Students participated in two hands-on training sessions (2 hours each) conducted by an American Registry for Diagnostic Medical Sonography certified sonographer. The sonographers were instructed by study coordinators to educate the students within the parameters of the study (focusing on specific views and techniques). Sonographers provided demonstrations in scanning technique and troubleshooting methods. Students developed their scanning technique by practicing on one another in small groups, under the supervision and guidance of the sonographer using a HHU unit.
Simulation-Based Scanning Sessions
The simulation sessions were not led by an expert instructor; all sessions were self-directed after a brief orientation of the simulation system by a study coordinator. Students participated in two self-directed hands-on training sessions (2 hours each) using a CAE Vimedix Ultrasound Simulator System (CAE Healthcare, Montreal, Quebec, Canada). During these sessions, students used the simulation system to develop their scanning technique and ability to identify pathologies. This high-fidelity simulation system has multiple learning modalities and settings, enabling students to progressively learn the basics of scanning technique. The simulation system allows students to practice scanning on “normal” patients and patients with a variety of preprogrammed cardiac pathologies, including LV systolic dysfunction, valvular dysfunction, and pericardial effusion. The simulation system uses a software-to-software probe-phantom system and also allows for simultaneous “cutaway” anatomic illustrations on a second viewing screen adjacent to the screen on which the ultrasound image is acquired.
Self-Directed Learning
As in phase 1, throughout the 4-week study, students in all educational programs were able to access HHU units to conduct self-directed practice in scanning. Participants were provided unlimited access to the HHU units and dedicated examination rooms for self-directed practice sessions. The self-directed portion was not a required element of the intervention and thus was not formally quantified.
Postintervention Assessment
Upon completion of the educational programs, students were assessed in two areas: interpretation of FCU images and scanning technique and image acquisition. Ability to interpret FCU images was assessed using an online multiple-choice examination, structurally similar to the preintervention examination (20 questions or cases). Ten questions focused on basic cardiac anatomy and recognition of standard echocardiographic views and 10 questions on identification of one of the five defined pathologies. Different images from the preintervention test were used to ensure that any improvements in scores were a result of the teaching intervention and not specifically learning the test items. Students were required to report their confidence in each answer (on a scale ranging from 0% to 100% in 10% intervals).
The technical ability of the students to accurately acquire high-quality FCU images was assessed by a practical examination. Each student conducted an FCU examination on a healthy male patient within a 10-min time period. Students were instructed to acquire images using our eight-view FCU protocol: A2C, apical four-chamber, A5C, PLX, and PSX with cuts at the aortic valve, mitral valve, left ventricle, and LV apex.
Data Analysis
Online examination scores were automatically tabulated and reported using our institutional database program (MEdTech). Each student was required to sign into the system to access the examinations, and their scores from each question were compiled for analysis. Confidence reports were collected, and the data were compiled. All data were analyzed by individual examination question. Compiled data sets were exported into SPSS version 17.0 for Windows for analysis.
Student FCU scans were evaluated independently by three expert (ASE level III) staff echocardiographers who were blinded to the teaching intervention. Each FCU scan was evaluated using two distinct parameters: scan quality and accuracy. Image quality scores were used to evaluate students’ technical ability to acquire satisfactory images. Image accuracy scores were used as a supplementary measure to further assess students’ fundamental knowledge of scanning principles (i.e., probe location required to acquire particular FCU views). Image accuracy was not considered a measure of evaluation of scanning technique.
Scan quality was assessed using a continuous scale with scores ranging from 0 (unacceptable/unreadable study) to 9 (ideal/best possible study). Accuracy was defined as a binary measure of whether the correct FCU view was acquired. To ensure a clear distinction between these two parameters, images that received unacceptable quality scores (zero) were automatically classified as inaccurate. Thus, only images that were of sufficient quality were further evaluated for accuracy. Each student was assigned an overall accuracy percentage score by determining the number of correctly identified views and dividing by the total views required (eight). Scores from each of the three evaluators were combined for analysis.
Mean scores were calculated for each individual, pathology, and the cohort for both the preintervention and postintervention evaluations. Mean improvement was calculated for each of these categories. Paired t tests were used to compare improvement from preintervention to postintervention for individuals and the cohort. P values < .05 were deemed significant. An analysis of covariance allowed comparison between groups while adjusting for baseline scores. All tests were two sided.
Interrater Reliability
To improve reliability, the mean of three assessors was used to obtain the student rating for each view and for the total number of correct views. The reliability coefficient of the raters’ mean was estimated as the between-student variance divided by the sum of the between-student variance and one third of the within-student variance. The variance components were estimated using an analysis-of-variance model with random effects for students and raters.
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